Glaucoma is the leading cause of blindness worldwide and the most common cause of optic neuropathy. Various forms of glaucoma leads to elevated intraocular pressure, and may also lead to damage to the optic nerve. If glaucoma or ocular hypertension is detected early and treated promptly with medications that effectively reduce elevated intraocular pressure, loss of visual function or its progressive deterioration can generally be ameliorated. Drug therapies that have been proven useful for the reduction of intraocular pressure include both agents that decrease aqueous humor production and agents that increase the outflow facility. Such therapies may be administrated in a number of different ways.
One example of administrating suitable therapies includes topical application to the eye, such as eye drops. However, one of the limitations of topical therapy is inadequate and irregular delivery of the therapeutic agent to the eye. For example, when an eye drop is applied to the eye, a substantial portion of the drop may be lost due to overflow of the lid margin onto the cheek. Moreover, compliance with a necessary drug regime is also always an issue with this method. For example, for some medications, 4 to 5 applications a day are required to achieve therapeutic drug levels.
Other suitable delivery mechanisms for therapeutic devices include injection at the pars plana. However, aside from discomfort for the patient, this method also requires that the patient return monthly.
Various ocular drug delivery implants have also been employed in an effort to improve and prolong drug delivery. One such example includes a reservoir drug-delivery device. A reservoir drug-delivery device is a device that contains a receptacle or chamber for storing the drug while implanted in the eye. However, reservoir drug devices are difficult to manufacture, difficult to achieve drug content uniformity (i.e., device to device reproducibility, particularly with small ocular devices), and carry the risk of a “dose dump” if they are punctured.
Another type of drug delivery device is a punctal plug device that is inserted into one or more of the tear ducts within the eye. However, because the geometry of the tear duct varies from person to person, there have been problems with plugs migrating within the tear duct. Other issues occur whereby the punctal plugs may inadvertently fall out of the eye.
Accordingly, there exists a need for a therapeutic delivery mechanism that allows for controlled and sustained release of ophthalmic drugs over a predetermined period of time, while sufficiently securing the delivery device within the eye so as to prevent inadvertent migration or removal of the delivery device.